OAuth 2.0 Token Introspection with NGINX and njs

This configuration enables NGINX to validate an authentication token against an authorization server by using OAuth 2.0 Token Introspection (RFC 7662). This solution uses the auth_request module and the NGINX JavaScript module to require authentication and perform the token introspection request.

By default, the client's authentication token is expected as a bearer token supplied in the Authorization header. If supplied elsewhere in the HTTP request, the $access_token variable must be configured to specify where to obtain the token.

Token introspection requests are authenticated. By default, the $oauth_client_id and $oauth_client_secret variables are used to perform HTTP Basic authentication with the Authorization Server. If only the $oauth_client_secret variable is specified then that value is used to perform authentication with a bearer token on the Authorization header.

Responses from the OAuth 2.0 authorization server are cached to minimize latency on each request.

If the introspection response contains member data then each member can be accessed as NGINX variables by using auth_request_set $new_variable $sent_http_token_membername;. Such variables can then be logged, used for conditional access control, and proxied upstream to provide identity metadata to the backend application.

The token introspection result is logged to the error log. Change the error_log severity level to affect verbosity.